SX50 -Filter Adapter and Lens Hood

Probably it's a little to soon to ask this, but it bothers me: in the manual at page 35 it says there is a filter adapter ring (FA-DC67A) for 67mm filters. Here I read there is also a 58mm filter adapter, much cheaper considering both the adapter ring and the smaller filters.

My first question is: if there is no difference whatever between the two (I'm thinking for instance of a black "frame" at the wide end), why preferred Canon the bigger one?

And another question: could be the filter adapter and the lens hood (LH-DC60, same page) simultaneously mounted?